Fire extinguishing sprinkler systems require that the system be tested periodically in order to prove the operability of the system, and, in particular to prove the operability of an alarm associated with the sprinkler system.
The alarm is provided in order to give an audible or visual warning that one or more of the sprinkler heads of the system have been activated, either accidentally, or in response to an existing fire condition, and is triggered by a water flow actuated switch positioned upstream of the sprinkler heads in the feed main to the sprinkler heads.
The water flow actuated switch is set for it to close at a flow rate in the feed main corresponding with, or not greater than, that produced by the actuation of a single one of the sprinkler heads.
As clearly, the activation of one of the sprinkler heads in order to test the system is not a viable method of testing the system, a separate test circuit must be provided in order to prove the water flow switch and to prove the alarm.
Such test circuits are well known in the art, and are comprised of an assemblage of fittings and interconnecting pipes providing a serial arrangement of a test valve connected to the feed main, a sight glass, and a connection from the metering device to a drain line. In addition, such test circuits include a separate drain line connected between the feed main and the drain line, and which is controlled by a drain valve independent of the test valve.
Thus, no fewer than nine separate fittings and nine separate lengths of threaded pipe are required in the assembly of a typical test circuit such as is in common usage, this producing a requirement for no less than twenty one separate threaded joints to be assembled in constructing the test circuit.